Once the archenteron reaches the animal end of the blastocoel, it folds over to one side (Fig.
This coincides with the bending of the archenteron and the emergence of mesodermal cells within the blastocoel.
The geometry of early cleavage is modified in this species such that the micromeres and the early embryonic pattern of msp 130 expression is absent and an unusually large number of mesenchyme cells enter the blastocoel
, where they begin directly forming the adult skeleton.
By this stage the larvae swam at the bottom of the dish anterior end up, buoyed by the abundant lipid reserves in the blastocoel of this region of the larva.
The blastocoel thus functions as a storage space for nutrients to support juvenile development.
2 h Blastula with blastocoel
9 h Hatching 21 h Gastrula, 140 [micro]m long and 120 [micro]m wide 1.
Indeed, Borojevic (1969) noted that larval cells migrate into the blastocoel
firstly from the posterior region of the coeloblastula, where vesicul ar cells are concentrated.
These specimens were for measurements of the thickness of the blastocoel wall, which cannot be obtained accurately in living embryos, because of optical reflections through the ectodermal layer.
This was caused by the expansion of the ectodermal layer, especially at the lateral blastocoel wall (Fig.
As cleavage proceeded, a blastocoel
formed and blastomeres with zooxanthellae moved into this space (Fig.
Blastocysts physiologically rarely contract so severely that their blastocoels
becomes an embryo when a condensation of cells, known as